Data from a study involving 500 related allogeneic haematopoietic stem cell transplantation (HSCT) donors demonstrate that the presence of clonal haematopoiesis of indeterminate potential (CHIP) mutations has no effect on overall survival of the recipients. A total of 92 CHIP mutations were identified in 80 donors (16%), with a median variant-allele frequency of 5.9%. The majority of patients (70) had a single detectable mutation. Patients who received stem cells harbouring CHIP mutations had an increased risk of graft-versus-host disease (HR 1.73, 95% CI 1.21–2.49; P = 0.003) and a reduced cumulative incidence of relapse and disease progression (multivariate HR 0.63, 95% CI 0.41– 0.98; P = 0.042). These findings suggest that the presence of one or more CHIP mutations should not preclude stem cell donation.